Stop referencing the crazy target/device stuff

We don't need Config.in and Makefile in target/device: defconfig files
are sufficient to describe the specificities of a board (architecture,
compilation flags, bootloader and kernel details, etc.).

However, a placeholder such as target/device will be kept in order to
host things such as kernel configuration files or various
board-specific patches.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

Config.in

@@ -11,7 +11,6 @@ config BR2_VERSION
 	option env="BR2_VERSION_FULL"
 
 source "target/Config.in.arch"
-source "target/device/Config.in"
 
 menu "Build options"
 

target/Makefile.in

@@ -1,6 +1,3 @@
 # make sure to put everything that is board-specific before the tarroot targets
 include target/generic/Makefile.in
 
-# this eventually adds the kernel target to TARGETS:
-include target/device/Makefile.in
-include target/xtensa/Makefile.in